Removal of CO2 from landfill gas with landfill leachate using absorption process

Abstract

Landfills produce methane and carbon dioxide. Typically, this gas is flared and the energy is lost. The objective of this study was the partial removal of carbon dioxide for the purification of methane from landfill gas. The experimental set up consisted of a model landfill gas mixture (50% CH4/50% CO2) in an absorption column with a 6cm diameter and 70cm height. A model of the absorption column was developed using COMSOL Multiphysics® and validated using experimental results. The column was filled with either ¼″ glass beads or 7.6mm clinoptilolite (zeolite) particles. Using leachate as the liquid phase resulted in slightly more removal of carbon dioxide than water (60.6% and 56.8%, respectively, with zeolite; and 63.4% and 61.5%, respectively, with glass beads). Using zeolite as packing compared to glass beads showed slightly less removal (56.8% and 61.5%, respectively, using water; and 60.6% and 63.4%, respectively, when using leachate). When zeolite was used as packing and reused leachate as the absorbent, the gas composition was in equilibrium after 2 recycles at a composition of 55% methane and 45% carbon dioxide. When glass beads were used as packing and reused leachate as the absorbent, the carbon dioxide removal was higher (63.4%) after the first use such that the carbon dioxide desorbed at the inlet of the pump in the subsequent recycles caused cavitation.